The present invention relates generally to electromagnetic contactors, and more particularly to a contactor which is coupled to an overload relay to form an electric motor starter that provides overcurrent protection in order to prevent current overloading to a load, i.e. a motor.
In electromagnetic starter applications, an overload relay is used to protect a particular load, such as a motor, from excessive currents. Known overload relays incorporate bi-metal switches and heaters in the overload relay connected in series with contacts of the contactor. However, these devices require separate invasive connections between the contactor and overload relay, and their presence increases the cost and size of the starter. Therefore, it would be desirable to have a smaller, lower cost overload relay having a simplified non-invasive connection to the contactor that eliminates the necessity for other devices connected to the contactor.
Another problem associated with the operation of a electromagnetic contactor is a tendency for a moveable contact carrier to lock during travel to and from an energized electromagnetic core. The random locking of the moveable contact carrier prevents the precise control of contactor timing required in industrial contacts.
Therefore, it would be desirable to have an electromagnetic contactor with an overload relay having a simplified non-invasive electrical connection through the overload relay to a contactor, that prevents cross-pole magnetic flux transfer and provides a smooth travel path for a moveable contact carrier in the contactor as it travels to and from an electromagnetic coil.